Apparatus for forming integral finned tubing



Sept. 25', 1945. v G. E. CLIFFORD 2,385,493

' APPARATUS FOR FORMING INTEGRAL FINNED TUBING Filed Feb. .25, 1942 2 Sheets-Sheet} A INVENTOR. GEORGE E. CLIFFORD Sept; 25, 1945. EMCLIFFORD 2,385,498

' APPARATUS 'FOR FORMING INTEGRAL FINNED TUBING Fild Feb. 23, 1942 2 Sheets-Sheet 2 v ATTORNEYS Patented Sept. 25, 1945 APPARATUS FOR FORMING INTEGRAL FINNED TUBING George E. Clifford, Detroit, Mich, assignor, by

mesne assignments, to Calumet and Hecla Consolidated Copper Company, Calumet, Mich, a

corporation of Michigan Application February 23, 1942, Serial No. 432,064

10 Claims.

' onto cylindrical tubes are not suitable for rolling fins onto tapered tubes. In order to provide a tapered tube with a continuous fin of uniform cross section and uniform pitch, a number of factors not present in the rolling of a fin onto a cylindrical tube must be taken into consideration.

In the first place, it will be appreciated that if one or more continuous, generally helical fins are formed on a tapered tube, and that if these fins are to have uniform pitch "or spacing throughout the tube, it will be necessary to provide the fins ata continuously changing helix angle.

With this in mind, it is an object of the present invention to provide a method and apparatus for rolling one or more fins onto a tapered tube in such a way as t provide one or more continuous, generally helical fins of constant spacing or pitch.

More specifically, it is an object of the present invention to roll a fin of the character described onto a. tapered tube by employing a forming roll having forming elements made up of separate circular discs assembled together'on an arbor and providing for a change in angularity of the arbor with respect to the axis of the tapered tube during the rolling operation.

It is a further object of the invention to provide apparatus for rolling a fin of the character described on a tapered tube, which employs a plurality of forming rolls disposed about the axis of the tapered tube and with the axis of the forming rolls inclined to and/or crossing the axis of the tapered tube at a small angle, in which opposite ends of the arbor supporting the forming rolls are mounted for generally radial movement along non-parallel paths whereby the angularity of the arbor with respect to the axis of the tapered tube is a function of the radial displacement of the forming roll with respect to the tapered tube.

Other objects of the invention will be apparent as the description proceeds and when taken in conjunction with the accompanying drawings,

wherein:

Figure 1 is a side elevation of a finned tapered tube made in accordance with the present invention;

Figure 2 is a plan view of the apparatus employed;

Figure 3 is an and elevation of one of the tool supporting heads,

Figure 4 is a section on the line 4-4, Figure 3; and

Figure 5 is a diagram illustrating the change in the helix angle with change in diameter.

Referring first to Figure 1, a tapered tube I0 is shown as provided with a single, continuous fin H. The fin is integral with the metal of the tube and is rolled thereon by an operation which will subsequently be described in detail. It is desirable that the cross section of the finshall remain uniform throughout the taper d" t be,

and that the spacing between adjacent co'nvlutions of the fin, or the pitch of the fin,f shall remain uniform. In order that these conditions shall be fulfilled, it is necessary for the fin to extend from the large end of the tube toward the small end of the tube at a.constantly increasing helix angle, as is clearly shown in Figure 1. It will be appreciated that in this figure the showing is more or less diagrammatic, the shape of the fin and the contour of the metal between successive convolutions of the fin i only approximate, and the taper of the tube is probably greater than would normally be provided. However, the present invention is capable of rolling a continuous fin of constant pitch onto a tapered tube having a very substantial taper, and having a very substantial difference in diameter at opposite ends thereof. Fig. 5 shows diagrammatically the change in helix angle as the radius is changed for the same axial advancement. Thus, 0-1) is the axial advancement in one-half revolution of the helix, a--c is a small radial dimension, and H a larger radial dimension. It will be noted that the helix angle of c-d is much greater than the helix angle of ef for the same axial dimension a,b.

The apparatus employed in Figure 2 comprises a supporting bed 20 to which is rigidly secured a frame structure. carrying a pair of tool supporting heads 22. The detailed structure of these heads will subsequently be described in detail, but for the present it is sufiicient to note that each includes adjustable bearings for supportin opposite ends of forming roll supporting arbors 23. The forming roll supporting arbors 23 may con veniently be three in number and arranged about the path of axial advance of the tapered tube,

which is indicated in this figure at 24. On each of the roll supporting arbors 23 are a pluralityof forming roll elements 25, each of which is circular, and which are shaped to roll the material of the tube 24 into the finned shape illustrated in Figure 1. Since the forming roll is made up of a plurality of forming roll elements, it will be understood that it is necessary to incline the axis of the arbors 23 with respect to the axis of advance of the tapered tube 24. More specifically, the arbors 23 are positioned so that their axes are crossed in space relative to the axis of the tube 24 at an angle which is substantially the complement of the helix angle of the fin bein rolled on the tube.

The forming operation is carried out by advancing the tube 24 axially through the space between the separate forming rolls. The tube is mounted for free rotation and the forming mils are positively rotated at a predetermined speed, as will later appear.

Since, as previously stated, it is necessary to provide for a constantly changing helix angle on the tapered tube, two additional relative motions must be introduced between each of the forming rolls and the tapered tube as the, tapered tube is advanced. In the first place, as will be obvious, it is necessary to withdraw the forming rolls in a generally radial direction to correspond to the increasing diameter being worked on as a result of the axial advance of the tapered tube. In addition there must be a correspondin continuous change in the angularity of the axis of each of the forming roll arbors with respect to the axis of the tapered tube. The mechanism which provides for these relative motions will be described subsequently.

In order to support the wall of the tube 24 during its axial advance through the heads 22 and through the space between the forming rolls, the following structure is provided: A tapered mandrel 30 is mounted for free rotation in a block 3| mounted to slide on the bed 20, suitable ways being provided as indicated at 32. Connected to the rear of the mandrel 30 is an air cylinder 33 or equivalent device by means of which a continuous force may be applied to the mandrel 30, urging the same to the right, as seen in Figure 2. This keeps the mandrel up firmly in the tapered tube and supports the material of the walls of the tube against the radial pressure developed by the formin rolls.

Driving means are provided for each of the forming roll arbors 23 and inciude driving links 35 interconnected through the medium of universal joints to the arbors 23 and to drive shafts 35, one such driving universal joint being indicated at 38. The driving shafts 35 are positively driven in unison through suitable gearing (not shown) which, in turn, is driven from a motor 31.

It is necessary to employ universal connections for the links 34 due to the change in angularity of the arbors 23, and due to the fact that none of the arbors 23 is parallel to the others.

Referring now to Figures 3 and a, one of the arbor supporting heads 22 is shown in detail. Since these heads are identical, only one will be described in detail. Each of the heads i made up of a main support 40 having an opening 48 formed therein for slidably receiving a rack 42, whose function will later be described. The upper portion of the support 40 is provided with a circular opening indicated in Figure 3 by the numeral 43. Mounted for rotation within the opening 48 is an adjusting ring 44 which has rack teeth 45 formed on a portion of its periphery to of slidable bearing blocks BI.

project from the bearing blocks Bl.

mesh with the teeth on the rack 42. The adjusting ring 44 is retained in position in the circular opening in the support 40 by suitable retainer rings 46. A pair of cam rings 41 are provided, the outer periphery of which fits closely within the circular space provided by the adjusting rin 34, as best seen in Figure 4. The interior of the cam rings 41 are provided with the camming profiles illustrated at 48 in Figure 3. As seen in Figure 3, separate camming profiles are provided, each of which cooperates with means for supporting one end of a roll supporting spindle.

Cam rings 41 are keyed to the adjusting ring 44 by suitable means indicated at 49 in Figure 3.

The interior of the adjusting ring 3 is provided with a plurality of pockets 5!], and between these pockets its inner surface is circular and supports a rotatable bearing block plate or holder 5|. The bearing block holder Si is provided with a gear segment 52 adapted to mesh with a worm 53 carried by a shaft 54 mounted in the main support 40. The shaft 54 is provided with an operating handwheel 55, as seen in Figure 3.

In order to permit independent rotation of the adjusting ring 44 with respect to the rotatable bearing block holder 5!, it is necessary to provide slots in the adjusting ring 34% to receive the shaft 54. These slots are shown at 56 and 51. As best seen in Figure 3, one of the pockets 50 is extended for a sufiicient space to receive the adjusting worm 53.

The bearing block holder 5| is provided with a plurality of guiding siots 88 for the reception The bearing blocks iii are provided with guiding keys 62 received within suitably formed cooperating slots at the side of the guiding slots 80. The inner end of each of the bearing blocks W has adjustably received therein a bearing 63 for one end of one of the forming roll arbors. Limited relative movement between the bearing 63 and the bearing block 6| is permitted to allow for the changes in angularity of the forming roll arbors.

Above the guideways S ll the bearing block holder 5| is provided with guiding openings 85 which receive in guiding relation rods 66 which At opposite sides of the bearing block holder 5|, each of the rods 56 is provided with a roller 61. These rollers 61 extend into the plane of the cam rings ll and engage the camming surfaces 38 thereof. The rods 86 project beyond the outer periphery of the bearing block holder 5| into the pockets or spaces 50 provided at the interior of the adjusting ring 44. These pockets, as best seen in Figure 3, are of substantial circumferential ex= tent to permit the relative adjustment between the parts, as will later be described. Compression springs Iii surround the outwardly project-= ing end of the rods 66 and bear against washers 'll retained on the rods by suitable means, such for example as the nuts l2. As will be apparent, the compression springs continuously urge the bearing blocks Bl outwardly and retain the rollers El in firm engagement with the cam surfaces 48. An important function of the compression,

springs 10 is to prevent the bearing blocks M from moving inwardly into engagement with each other after the tube has passed beyond the forming rolls.

Referring again to Figure 2, in conjunction with Figure 3, the slidable block 3! is connected to a slidable plate mounted in suitable guideways 88a. The plate 80 is slidable with the head 3| and is supported on a shelf 8! forming a part of the bed 20. The slidable plate 80 has mounted thereon a pair of members 82, 83 which define therebetween an inclined slot 84. To vary the inclination of the slot 84, each of the members 82 and 83 is mounted for adjustment adjacent one end about a pivot 85, and has an elongated arcuate slot 86 at its other end.

Referring now to Figure 3, the racks 42 have rollers 81 secured adjacent their outer ends by suitable pins such as a pin 88. The rollers 81 are received between members 82 and 83 so that upon longitudinal movement of the head 3|, a transverse movement will be imparted to the rack 42 in accordance with the inclination of the slot 84.

Attention is directed to the fact that the guideways 60 in which thebearing blocks 6| are slidably adjustable, are located at a small angle with respect to a line radial of the tapered tube 24. The angularity of the guideways 60 may be computed so that upon outward displacement of the bearing 63 in accordance with the taper of the tube 24,.the necessary variation in helix angle will be accomplished automatically.

The structure making up the improved apparatus for rolling fins on tapered tubes has now been described, but for a complete understanding of the same, the operation will be described in some detail.

The apparatus is capable of accommodating tubes of substantial difference in size. and it is accordingly necessary to be able to adjust the initial radial spacing of the forming roll arbors 23, as well as to set these arbors at a predetermined angle with respect to the axis of the tapered tube. In order to carry these initial adjustments, the handwheel 55 is employed. It will be appreciated that so long as the racks 42 are stationary, the adjusting rings 44 will be retained against rotation. The main support 40 is, of course, stationar at all times. Under these circumstances, rotation of the handwheel 55 will effect a rotational adjustment of the corresponding bearing block holder 5|, through the medium of the worm 53 and the worm gear teeth 52. The bearing block holder 5i is retained for this rotational adjustment in the central opening in the adjusting ring 44 and is retained against axial displacement by the presence of the cam rings 41. Since at this time the adjusting ring 44 is stationary, rotation of the bearing block holder 5| will cause the various rollers 61 carried by the bearing block rods 66 to move along their cooperating cam surfaces 48. Thus for example, if the handwheel 55 is turned in such a direction as to rotate the bearing block holder 5| in a counterclockwise direction as seen in Figure 3, this will result in camming the bearing blocks 6| inwardly. It will be appreciated that this will also have the effect of changing the angularity of the forming roll arbors, since the angularity of these arbors is in part a function of their radial position. However, by a proper correlation between the initial settings of the bearing blocks and the relative rotational positioning ofthe bearing block holders 51 in the two spaced heads 22, the proper initial relationship can readily be established. If desired, a separate adjustment ofthe adjusting ring can be 1119116, 85 by securing the roll supporting pin 88 for adjustment longitudinally of rack 42.

Having set the bearing blocks and accordingly the forming roll arbors at the desired position with respect to radial displacement and angular adjustment, the handwheel 55,.is released. By

virtue of the worm and worm wheel relationship, this will retain the bearing block holders 5| against further rotational movement during the succeeding operation of the apparatus.

A tapered tube with its small end extending toward the heads 22 is positioned over the mandrel 38 so that the mandrel seats up firmly into the tapered tube. Pressure is applied through the cylinder 33, continuously urging the mandrel 30 and the tapered tube 24 forwardly into engagement with the forming rolls. The force applied to the mandrel 30 is merely sufllcient to prevent the reactionary axial pressure from the fin forming operation from displacing the mandrel from the required position for supporting the tube wall. The mandrel is heldtight enough to prevent a decrease in the inside diameter of the tube during the finning operation. Rotation is imparted to the forming rolls through the motor 31 and through the driving links 34 previously described. The forming elements 25 making up the forming rolls are of such shape that the metal of thetapered tube is formed gradually through a plurality of revolutions until the ultimate in shape is achieved. Rotation is imparted to the tapered tube and to its supporting mandrel through the engagement between the forming rolls and the tapered tube, and as soon as the fin formation commences, this rotation is also combined with an axial advance of the tapered tube at a rate sufiicient to permit the proper formation of the fins. In other words, as the fin is formed on the tapered tube, the tube ad-' vances one pitch for each revolution thereof.

Since the plate 80 carrying the slot forming members 82 and 83 advances simultaneously with the head 3|, a corresponding transverse movement of the racks 42 results. This movement of the racks 42, as best seenin Figure 2, results in a corresponding rotation of the adjusting ring 44 and the cam rings 41 keyed thereto. Since at this time the bearing block holder Si is stationary, this rotation of the cam rings 41 will result in outward movement of the bearing blocks 6i It will be appreciated that the outward move ment of the bearing block BI is permitted by a relative withdrawal of the cam surface 48 and that the bearing blocks Bl follow outwardly by virtue of the force exerted through the forming rolls, as well as by virtue of the force acting in the same direction of the compression springs 10.

As previously stated, the guideways 60, in which the bearing blocks iii are slida-ble, are disposed at a definitely predetermined angle, which ordinarily will be other than radial of the tapered tubes. Accordingly, as the bearing blocks GI and the ends of the forming roll arbors carried thereby, are moved outwardly to accommodate the increasing diameter of the tapered tube,

there will be a change in angularity of the forming roll arbors with respect to the axis of the tapered tube. The inclination of the guides 60 will normally be computed so that the changein angularity of the arbors of the forming rolls 'with respect to the axis of the tapered tube, is

such that the pitch or spacing of adjacent convolutions of the firi I I remains constant irrespective of the diameter of the tube.

When the fin has been formed on the complete length of the tube, the tube will have advanced ments 82 and 83 so that when the mandrel 3'0 is back in initial position, the parts are in position for a new operation.

In the initial set up, each forming roll supporting arbor normally occupies a plane parallel to the nearest straight line element of the tapered tube, and is inclined in this plane from the projection of the axis of the tube by an amount depending on the pitch of the fin and the diameter of the tube at its small end. If preferred, the axes of the arbors may occupy planes parallel to the axis of the tube, and the forming roll elements may be of increasing diameter from the left-hand end to the right as viewed in Figure 2.

It was previously stated that one of the pockets 50 formed on the interior of the adjusting ring 44 was continued for a space sufficient to provide clearance for the adjustable worm 53. Itwill be appreciated that if desired the interior portion of the adjusting ring 44 adjacent the worm 53, may be provided with a slot of less width, suflicient only to accommodate the worm 53, so that the edges of this slot will provide additional guiding support for the bearing block holder 5| at that point.

It will be understood that instead of formin the fin on the tapered tube progressively from the small end toward the large end, it is possible if preferred to reverse the operation and form the fin progressively from the large end toward the small end. This would involve reversing the direction of action of the air cylinder 33, and reverse] of the supporting mandrel 30. As the fin-- ning operation progresses, the forming rolls would be cammed inwardly to correspond to the decreasing diameter of the tube. The continuous inward movement of the rolls would result in a continuous adjustment of the angularity of the rolls so as to form a fin having a constant axial pitch.

In the foregoing description, primary reference has been made to the formation of a single continuous fin, but it is apparent that it would be possible if preferred to form a plurality of fins, similar to the formation of a plural" thread in threading work.

While I have illustrated a specific embodiment of my improved fin forming apparatus and have described the method of forming fins on tapered tubes in considerable detail, it will be appreciated that this has been done solely to enable those 1. Apparatus for rolling helical fins on tapered tubes which comprises means for supporting a tapered tube for combined axial and rotational movement, a forming roll arbor, a fin-forming roll on said arbor and means automatically operated in accordance with axial advance of said tube for positively effecting simultaneous movement of said arbor generally radially of the axis of said tube and changing the helix angle of said arbor as occasioned by the taper of said tube.

2. Apparatus for rolling helical fins on tapered tubes which comprises a bed, a tapered mandrel mandrel, and means responsive to axial movement of said mandrel fOr automatically effecting simultaneous radial and helix angular adjustment of said arbor with respect to the axis of said mandrel as occasioned by the taper of said tube.

3. Apparatus for rolling helical fins'on tapered tubes which comprises a bed, a tapered mandrel adapted to fit within a tapered tube to be finned, means supporting said mandrel on said bed for movement axially of said mandrel, means for exerting a pressure on said mandrel tending to move said mandrel axially, an arbor for supporting a forming roll at the side of said mandrel, a finforming roll on said arbor, means for rotating said arbor, manually operable means for adjusting said arbor generally radially of said mandrel, associated means for adjusting said arbor in helix angle with respect to the axis of said mandrel, and means responsive to axial movement of said mandrel for automatically effecting simultaneous radial and angular adjustment of said arbor with respect to the axis of said mandrel to change the helix angle of said arbor as occasioned by the taper of said tube.

4. In a machine for rolling fins on tapered tubes, means for supporting a tapered tube for axial advance, a forming roll arbor spaced laterally from the path of advance of said tube, means for rotating said arbor, bearing blocks at opposite ends of said arbor, a support for each of said blocks providing a guideway extending generally radially of said tube, means for effecting separate generally radial adjustment of said blocks to accommodate differently tapered tubes, means for efiecting separate adjustment of said blocks circumferentially of said tube to vary the angularity of said arbor and the pitch of fins formed by said machine, means operable in accordance with advance of said tube for effecting simultaneous generally radial movement of said blocks, said guideways being so disposed that said radial movement of said blocks results in angular movement sufficient to preserve uniform pitch on the fins formed by said machine.

erally radial guideways, bearing blocks in said.

guideways, forming roll arbors supported at opposite ends by pairs of said blocks, means for effecting relative rotationa1 adjustment of said plates to vary the angularity of said arbors with respect to the axis of said tubes, and means automatically operable in timed relation to advance of said tubes to effect a generally radial movement of said blocks whereby to provide a corresponding generally radial and angular adjustment of said arbors with respect to said tubes.

6. Apparatus for rolling fins on tapered tubes comprising means for supporting a tapered tube for axial advance, a pair of axially spaced plates surrounding the path of advance of said tubes, said plates each provided with a plurality of generally radial guideways, bearing blocks in said guideways, forming roll arbors supported at onposite ends by pairs of said blocks, camming means for each of said plates rotatable about the axis of advance of said tubes and engaging with said blocks for effecting generally radial adjustment of said blocks, means for effecting relative rotational adjustment of said plates to vary the angularity of said arbors with respect to the axis of said tubes, and means automatically operable in timed relation to advance of said tubes to effeet a generally radial movement of said blocks whereby to provide a corresponding generally radial and angular adjustment of said arbors with respect to said tubes.

7. Apparatus for rolling fins on tapered tubes comprising means for'supporting a tapered tube for axial advance, a pair of axially spaced plates surrounding the path of advance of said tubes, said plates each provided with a plurality of gen erally radial guideways, bearing blocks in said guideways, forming roll arbors supported at opposite ends by pairs of said blocks, camming means for each of said plates rotatable about the axis of advance of said tubes and engaging with said blocks for efiecting generally radial adjustment of said blocks, means for effecting relative rotational adjustment of said plates to vary the angularity of said arbors with respect to the axis of said tubes, and means automatically operable in timed relation to advance of said tubes to effect a generally radial movement of said blocks whereby to provide a corresponding gen erally radial and angular adjustment of said arbors with respect to said tubes, said last named means comprising camming mechanism connected to both of said camming means and perable automatically in accordance with advance of said tube.

8. Apparatus for rolling fins on tapered tubes comprising means for supporting a tapered tube for axial advance, a pair of axially spaced plates surrounding the path of advance of said tubes, said plates each provided with a plurality of generally radial guideways, bearing blocks in said guideways, forming roll arbors supported at opposite ends by pairs of said blocks, camming means for each of said plates rotatable about the axis of advance of said tubes and engaging with said blocks for effecting generally radial adjustment of said blocks, means for eifecting relative rotational adjustment of said plates to vary the angularity of said arbors with respect to the axis of said tubes, and means automatically operable in timed relation to advance of said tubes to effeet a generally radial movement of said blocks whereby to provide a corresponding generally radial and angular adjustment of said arbors with respect to said tubes, said last named means comprising a pinion connected to each of said camming means, a rack meshing with each of said pinions, followers connected to each of said racks, and means providing inclined surfaces engaging said rollers, said last means being connected for advance in accordance with advance of said tube. 9. Apparatus for rolling fins on pered tubes comprising means for supporting a tapered tube for axial advance, a pair of axially spaced plates surrounding the path of advance of said tubes, said plates each provided with a plurality of guideways extending at a small angle to a line radial of the axis of said tube, bearing blocks in said guideways, forming roll arbors supported at opposite ends by pairs of said blocks, means for eflecting relative rotational adjustment of said plates to vary the' angularity of said arbors with respect to the axis of said tubes, and means automatically operable in timed relation to advance of said tubes to effect a generally radial movement of said blocks whereby to provide a corresponding generally radial and angular adjustment of said arbors with respect to said tubes.

10. Apparatus for rolling fins on tapered tubes comprising means for supporting a tapered tube for axial advance, a pair of axially spaced plates surrounding" the path of advance of said tubes, said plates each provided with a plurality of guideways extending at a small angle to a line radial of the axis of said tube, bearing blocks in said guideways, forming roll arbors supported at 

